KeyPoint描述符OpenCV

Question

我试图了解如何在KeyPoint中为给定的OpenCV获取描述符。到目前为止，我的代码如下：

#include <iostream>
#include "opencv2/opencv.hpp"

typedef cv::Mat Image;

int main(int argc, const char * argv[])
{

    Image imgA = cv::imread("images/buddhamulticam_total100.png",
                              CV_LOAD_IMAGE_GRAYSCALE);
    Image imgB = cv::imread("images/buddhamulticam_total101.png", 
                            CV_LOAD_IMAGE_GRAYSCALE);

    cv::Ptr<cv::FeatureDetector> detector = 
                    cv::FeatureDetector::create("ORB");
    cv::Ptr<cv::DescriptorExtractor> descriptor = 
                    cv::DescriptorExtractor::create("ORB");

    std::vector<cv::KeyPoint> keyPointsA, keyPointsB;

    keyPointsA.push_back(cv::KeyPoint(0,0,5));
    keyPointsB.push_back(cv::KeyPoint(10,10,5));

    cv::Mat descriptorA, descriptorB;
    descriptor->compute(imgA, keyPointsA, descriptorA);
    descriptor->compute(imgB, keyPointsB, descriptorB);

    std::cout << "DescriptorA (" << descriptorA.rows << "," <<
                descriptorA.cols << ")" << std::endl;
    std::cout << "DescriptorB (" << descriptorB.rows << "," 
              << descriptorB.cols << ")" << std::endl;
    return 0;
}

问题是我在描述符中没有数据。我遗漏了什么？您能更详细地解释传递给KeyPoint对象的参数是什么吗？我是计算机视觉+ OpenCV的新手，所以一个更好的解释(比OpenCV的文档)可能会有帮助。

Answer 1

您试图在点(0,0)和(10,10)上计算ORB，但是它们太靠近图像边界，因此ORB无法计算这些位置的描述符。ORB (以及其他二进制描述符)过滤掉它们。

编辑:既然你问的是用法，我就在编辑答案。你应该把整个图像传递出去。我把它用作：

Ptr<FeatureDetector> detector = FeatureDetector::create(detector_name);
Ptr<DescriptorExtractor> descriptor = DescriptorExtractor::create(descriptor_name);

detector->detect(imgK, kp);
descriptor->compute(imgK, kp, desc);